CAB (shortened about 1825 from the Fr. cabriolet, derived from cabriole, implying a bounding motion), a form of horsed vehicle for passengers either with two ("hansom") or four wheels ("four-wheeler" or "growler"), introduced into London as the cabriolet de place, from Paris in 1820 (see Carriage). Other vehicles plying for hire and driven by mechanical means are included in the definition of the word "cab" in the London Cab and Stage Carriage Act 1007. The term "cab" is also applied to the driver's or stoker's shelter on a locomotive-engine.

Cabs, or hackney carriages, as they are called in English acts of parliament, are regulated in the United Kingdom by a variety of statutes. In London the principal acts are the Hackney Carriage Acts of 1831-1853, the Metropolitan Public Carriages Act 1869, the London Cab Act 1896 and the London Cab and Stage Carriage Act 1907. In other large British towns cabs are usually regulated by private acts which incorporate the Town Police Clauses Act 1847, an act which contains provisions more or less similar to the London acts. The act of 1869 defined a hackney carriage as any carriage for the conveyance of passengers which plies for hire within the metropolitan police district and is not a stage coach, i.e. a conveyance in which the passengers are charged separate and distinct fares for their seats. Every cab must be licensed by a licence renewable every year by the home secretary, the licence being issued by the commissioner of police. Every cab before being licensed must be inspected at the police station of the district by the inspector of public carriages, and certified by him to be in a fit condition for public use. The licence costs £2. The number of persons which the cab is licensed to carry must be painted at the back on the outside. It must carry a lighted lamp during the period between one hour after sunset and one hour before sunrise. The cab must be under the charge of a driver having a licence from the home secretary. A driver before obtaining a licence, which costs five shillings per annum, must pass an examination as to his ability to drive and as to his knowledge of the topography of London.

General regulations with regard to fares and hiring may be made from time to time by the home secretary under the London Cab and Stage Carriage Act 1907. The hiring is by distance or by time as the hirer may decide at the beginning of the hiring; if not otherwise expressed the fare is paid according to distance. If a driver is hired by distance he is not compelled to drive more than six miles, and if hired by time he is not compelled to drive for more than one hour. When a cab is hired in London by distance, and discharged within a circle the radius of which is four miles (the centre being taken at Charing Cross), the fare is one shilling for any distance not exceeding two miles, and sixpence for every additional mile or part of a mile. Outside the circle the fare for each mile, or part of a mile, is one shilling. When a cab is hired by time, the fare (inside or outside the circle) is two shillings and sixpence for the first hour, and eightpence for every quarter of an hour afterwards. Extra payment has to be made for luggage (twopence per piece outside), for extra passengers (sixpence each for more than two), and for waiting (eightpence each completed quarter of an hour). If a horse cab is fitted with a taximeter (vide infra) the fare for a journey wholly within or partly without and partly within the four-mile radius, and not exceeding one mile or a period of ten minutes, is sixpence. For each half mile or six minutes an additional threepence is paid. If the journey is wholly without the four-mile radius the fare for the first mile is one shilling, and for each additional quarter of a mile or period of three minutes, threepence is paid. If the cab is one propelled by mechanical means the fare for a journey not exceeding one mile or a period of ten minutes is eightpence, and for every additional quarter mile or period of 2½ minutes twopence is paid. A driver required to wait may demand a reasonable sum as a deposit and also payment of the sum which he has already earned. The London Cab Act 1896 (by which for the first time legal sanction was given to the word "cab") made an important change in the law in the interest of cab drivers. It renders liable to a penalty on summary conviction any person who (a) hires a cab knowing or having reason to believe that he cannot pay the lawful fare, or with intent to avoid payment; (b) fraudulently endeavours to avoid payment; (c) refuses to pay or refuses to give his address, or gives a false address with intent to deceive. The offences mentioned (generally known as "bilking") may be punished by imprisonment without the option of a fine, and the whole or any part of the fine imposed may be applied in compensation to the driver.

Strictly speaking, it is an offence for a cab to ply for hire when not waiting on an authorized "standing," but cabs passing in the street for this purpose are not deemed to be "plying for hire." These stands for cabs are appointed by the commissioner of police or the home secretary. "Privileged cabs" is the designation given to those cabs which by virtue of a contract between a railway company and a number of cab-owners are alone admitted to ply for hire within a company's station, until they are all engaged, on condition (1) of paying a certain weekly or annual sum, and (2) of guaranteeing to have cabs in attendance at all hours. This system was abolished by the act of 1907, but the home secretary was empowered to suspend or modify the abolition if it should interfere with the proper accommodation of the public.

At one time there was much discussion in England as to the desirability of legalizing on cabs the use of a mechanical fare-recorder such as, under the name of taximeter or taxameter, is in general use on the continent of Europe. It is now universal on hackney carriages propelled by mechanical means, and it has also extended largely to those drawn by animal power. A taximeter consists of a securely closed and sealed metal box containing a mechanism actuated by a flexible shaft connected with the wheel of the vehicle, in the same manner as the speedometer on a motor car. It has, within plain view of the passenger, a number of apertures in which appear figures showing the amount payable at any time. A small lever, with a metal flag, bearing the words "for hire" stands upright upon it when the cab is disengaged. As soon as a passenger enters the cab the lever is depressed by the driver and the recording mechanism starts. At the end of the journey the figures upon the dials show exactly the sum payable for hire; this sum is based on a combination of time and distance.